In applications of biomedical implants or remote human/equipment health monitoring, where replacing batteries can be difficult, a self-powered solution relying on harvested energy is highly desirable. Meanwhile, high-quality batteries having low leakage current and thus a long lifetime have to be used, and, in some cases, the battery issue has been one of the main technical challenges. Capability of harvesting energy from the ambient is desired for these applications; however, the existing energy harvesting solutions are mostly based on assembly of discrete components. As a result, they are too big to meet the form factor requirement and energy losses associated with connections of the discrete components largely reduce the efficiency of the system and the energy level that can be harvested.